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J.-H. MEYER. DENTAL FURNACE.

No. 532,681. 7 Patented Jan. 15, 1895.

. Ni'rnn STATES PATENT OFFICE.

JOHN H. MEYER, OF NEW YORK, N. Y.

DENTAL FUR-NAQE.

SPECIFICATION forming part of Letters Patent No. 532,681, dated January 15, 1.895.

v Application filed October 31,1894. Serial No. 527,535- (Nomodeh) To all whom it may concern.- I

Be it known that I, JOHN H. MEYER, a citi zen of the United States, residing at 159 West Thirty-fourth street, in the city, county, and State of New York, have invented a new and useful Improvement in Dental Furnaces, of

j which the following is a specification.

tion of the furnace for carrying on, in an economical, rapid and efficient manner, the

operations of drying, baking and annealing porcelain and other substances for block or bridge-work.

The invention is illustrated in the annexed drawings, in which- Figure l, is a partly sectional front elevation oftheimproved dental furnace, with the muffles or retorts in end view. Fig. 2, is a partly sectional side elevation of the dental furnace. Fig. 3, is a rear elevation of the same. Fig. 4, is a top view of a dental furnace without the annealing or cooling retort, but with a retort or muffle located in the elbow of the furnace fluefor preliminary heating or drying of the substance to be subsequently baked in the muffle or retort of the main furnace chamber. Fig. 5, is a perspective of the muffle to be located in the furnace fiue.

'Referring to the drawings, the numeral 1 designates the body portion or main chamber of the furnace proper, which may have any suitable or convenient form and dimensions. In this chamber 1, is located, as shown 'in Figs. 1 and 2, a muffle or retort 2 having at its front end a door or cover 3, as shown.

The muffle 2 may be supported at each end by the furnace walls; and aprons 4 and 5 may be provided, if desired. It is preferable to provide the furnace chamber 1 with a lining 6, Fig. 2, of fire clay, or other suitable mate- ,rial to assist in retaining the heat, so that a Very high temperature may be maintained for completing the baking operation.

The required heat may be obtained by any suitable burner 7, located beneath the furnace body.

In the elbow of the f urnace'flue 8 is located a retort or muffle 9 to utilize the heat that baking operation.

' muffle in the furnace flue is a very important would otherwise be wasted; and this muffle is adapted more particularly for the purpose of subjecting to-a preliminary heating and thereby drying and partially baking the porcelain or other substance before it is placed in the lower muffle 2 for completion of the This arrangement of a improvement, especially for facilitating rapid work, as a high degree of heat ascends through the furnace flue. It is preferable to support this muffle 9 in the elbow of the flue, so that it will interfere as little as possible with the draft. The muffle '9 may project partly through the flue, as shown, and it may be supported in .any conveniehtmanner, as by a pin 10 at one end and also by resting on the partly cut away wall of the flue.- One end of this muffle 9 is provided with a door 11, and in one or both ends a vent. 12 may be provided, for escape of vapor froin the sub- -stances being dried. Asimilarvent 13 may be arranged in the top of the muffle, and these vents may be controlled by plugs, or otherwise. An apron 14 is provided at the front end of the'flue muffle. ing 15, of fire clay, or other refractory material, and the flue and its lining are made to converge toward the sides of the muffle 9, as shown; The muffle 9 is preferably flatonits bottom and is made long enough to receive two or more plates or forms at the same time.

After a partial or preliminary heating or drying of a charge is effected in the muffle 9 the charge will be removed and then placed in the lower retort or muffle 2 where the bak ing will becompleted.

For the purpose of cooling and annealing the baked material series of retort-s or muffies In the flue 8 is a linstance to be subsequently baked in the furnace muffle, the said rnnflle 9 being provided with vents, and the flue lining 15 converging at its upper end toward the sides of said muffle 9 and composed of refractory material, substantially as described.

2. The combination with a dental furnace having the inclosed muflie 2 and provided with a fine having the mnffle 9 therein, of the annealing and cooling inufiies 16 located in KO chambers on the opposite sides of the main furnace chamber, and the shutters 18 for closing in said annealing lnuffles, substantially as described.

JOHN H. MEYER. Witnesses:

C. D. ALLEN, T. A. WADSWORTH. 

